The art has long recognized compositions that can be applied as protective coatings or finishes (herein coatings) to metal, wood, glass, ceramic, masonry and polymeric materials. Also known are coatings that include pigments or dyes in their compositional makeup. The colorants and coatings must be applied concurrently.
For example, U.S. Pat. Nos. 6,479,561; 6,586,051; 6,727,372; 6,699,578; 5,827,923; 6,727,372 and 6,953,618 disclose mixing dyes in polyurethane or acrylic coatings which are then applied to a substrate. The technology thus disclosed does not enable applying a protective polyurethane or acrylic coating to an article, and color the coating subsequent to the application nor does it permit coloring only restricted/selected areas. Additionally, the disclosed technology does not enable creating a color gradient.
U.S. Pat. No. 6,068,797 disclosed a method of preparing a shaped article having a photochromic coating and a curable photochromic powder coating composition. The method includes applying curable powder coating composition to the interior of a mold, the powder coating compositions including a photochromic material. Following the application, the coating is cured and a polymerizable organic casting composition is then charged into the mold and polymerized. The resulting shaped article having a photochromic coating on its surface is then removed from the mold.
A method of tinting a sheet of transparent polyurethane comprising a coloring operation followed by a fixation operation is disclosed in U.S. Pat. No. 4,454,170. The coloring operation is carried out by immersing the sheet in an agitated bath containing dispersed colorants in an aqueous solution. The fixation operation is carried out through rinsing in a boiling aqueous solution of sodium alkyl sulfonate.
U.S. Pat. No. 6,749,646 disclosed tinting articles molded from a polymeric resin. The process entailing immersing the molded article in a dye bath that contains water, dye, a carrier and an optional surfactant.
U.S. Pat. No. 6,733,543 disclosed dyeing a molded article by immersing at least a portion thereof in a dyeing bath, retaining the portion in the bath for a time sufficient to allow dye to diffuse into the article. The molded article comprises a polymeric resin and the dyeing bath contains in addition to dye, water, a plasticizing agent and a leveling agent.
GDR Patent No. 116 520 disclosed a method of preparing photochromic polymer systems which include photochromic ortho-nitrobenzyl compounds added to reaction systems which lead to polyurethanes. EP146,136 disclosed an optical element with a photochromic coating, such as a polyurethane lacquer in which are incorporated one or more phototropic substances. JP3-269507 disclosed a coating material contains block polyisocyanate, polyol and photochromic material that is applied on a lens and is cured by heating in order to form a primer layer. A hard coat layer consisting of silicone is provided on the polyurethane primer layer.
U.S. Pat. No. 6,187,444 disclosed an article comprising a substrate and a polyurethane coating on at least one surface of the substrate, the coating containing photochromic compound. The photochromic polyurethane coating is prepared from components comprising an organic polyol comprising sections of hard and soft segment-producing polyols; an isocyanate, photochromic compound(s) and optional catalyst.